Comparative study of four known species of the genus Acrobeles von Linstow, 1877 (Nematoda, Cephalobidae) with ‘single’ and ‘double’ cuticle from coastal dunes in Spain

Abstract The nematode genus Acrobeles is composed of two morphological groups distinguished by the presence (‘double’ cuticle) or absence (‘single’ refringent inner layer cuticle. In present study, four species this genus, with ‘single’ cuticle ( ciliatus and cylindricus ) ‘double’ aenigmaticus complexus are studied from coastal dunes in Spain. This study provides detailed morphometrical analyses for species, while molecular analysis, based on 18S 28S ribosomal DNA, provided A . scanning electron microscopy, which obtained first time These revealed differentiations between both groups, appearing as related monophyletic entities. subgenera Seleborca , formerly considered separate genera, proposed to accommodate groups.